altered andesite buckwheat, Eriogonum robustum, Nevada, Virginia Range, Geiger Grade, Steamboat Creek - Truckee Meadows drainage, elevation 1630 m (5350 ft).

This distinctive buckwheat is the signature rare species that is endemic to these peculiar "altered andesite" soils in the foothills surrounding the greater Reno-Sparks area of far western Nevada. Deep hydrothermal alteration of these volcanic deposits left behind sulfide minerals, which slowly oxidize to sulfuric acid as they become exposed at the surface. This creates patches of highly acidic (pH 3-4), brownish orange to white soils that are largely barren of vegetation. Those few species that evolve to tolerate these harsh soil conditions enjoy reduced competition from other vegetation, but in this case also become dependent on such conditions and don't survive anywhere else.

This species is closely related to Eriogonum lobbii, a common higher-elevation species of the Sierra Nevada to the west, of which it was once considered a variety. The two are fully distinct, however, with E. lobbii being a smaller species with prostrate stems and less branched flower heads.